pre-mortem

pre-mortem is a skill for Claude Code, Codex from martineserios/thebrana. It costs 104 tokens per session (4,224 once invoked), scanned A, a copy of pre-mortem, MIT.

A pre-mortem is a planning exercise that imagines a project has already failed and works backward to find possible causes.

In plain words
What is it for?
Use it before launching a product, campaign, or major initiative, or before important hiring, investment, partnership, and project decisions.
Why use it?
It surfaces risks before launch, including concerns that may be overlooked when a team is confident in its plan.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: positional $N argument; installed under .agents/ (shared by several agents).

Good fit Use it before launching a product, campaign, or major initiative, or before important hiring, investment, partnership, and project decisions.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/martineserios/thebrana/pre-mortem
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add martineserios/thebrana --skill pre-mortem
Clone the repo
git clone --depth 1 https://github.com/martineserios/thebrana

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for pre-mortem

README.md
[![agentmods](https://agentmods.dev/badge/skills/martineserios/thebrana/pre-mortem.svg)](https://agentmods.dev/skills/martineserios/thebrana/pre-mortem)
Your own site
<a href="https://agentmods.dev/skills/martineserios/thebrana/pre-mortem"><img src="https://agentmods.dev/badge/skills/martineserios/thebrana/pre-mortem.svg" alt="Measured on agentmods" height="20"></a>
Per session 104 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 4,224 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin 100% copy Near-identical to another mod in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00104 $0.04224
Opus 5 $0.00052 $0.02112
Sonnet 5 $0.00021 $0.00845
Haiku 4.5 $0.00010 $0.00422

Measured 7d ago against content hash 78d14315ce9f, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

pre-mortem scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 7d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

This is a copy

100% identical to pre-mortem — 0 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

.agents/skills/pre-mortem/SKILL.md · 638 lines

How it starts

The opening of the file, as written. The whole thing — 638 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Pre-Mortem

Imagine your project has failed spectacularly—then work backward to identify why. Apply Gary Klein's "prospective hindsight" technique to catch failures before they happen.

When to Use This Skill

  • Before launching a product, campaign, or major initiative
  • Before making an important decision (hiring, investment, partnership)
  • Starting a project to identify risks the team hasn't considered
  • When overconfident and everyone agrees the plan is great
  • Before committing resources to a significant undertaking
  • In team planning to surface concerns people might hesitate to share

Methodology Foundation

Aspect Details
Source Gary Klein (1989), cognitive psychologist, naturalistic decision making pioneer
Expert Klein's research shows pre-mortems increase accuracy of identifying reasons for outcomes by 30%
Core Principle "Prospective hindsight" - imagining an event has already occurred dramatically improves our ability to explain it. The future feels distant; the past feels real.

What Claude Does vs What You Decide

Claude Does You Decide
Structures production workflow Final creative direction
Suggests technical approaches Equipment and tool choices
Creates templates and checklists Quality standards
Identifies best practices Brand/voice decisions
Generates script outlines Final script approval

What This Skill Does

  1. Surfaces hidden risks - Finds dangers invisible to forward-looking planning
  2. Gives permission to criticize - Team members can voice concerns safely
  3. Reduces overconfidence - Counters planning fallacy and optimism bias
  4. Improves plans before execution - Fix problems when they're cheap to fix
  5. Creates psychological safety - "We're imagining failure" feels safer than "I think this will fail"

How to Use

Run a Pre-Mortem

Run a Pre-Mortem on this project:
[describe the project, product, or decision]

It's one year from now and this has failed completely. What happened?

Read the full file on GitHub · 638 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 7d ago First seen · 638 lines · 104 tokens per session scan A 78d14315ce9f

Subscribe to this mod's changes

pre-mortem is a skill published in the GitHub repository martineserios/thebrana (3 stars, last pushed 3d ago), licensed MIT. It adds 104 tokens to every session and 4,224 once invoked, about $0.0005 per session on Opus 5. A static security scan graded it A with 0 findings. It is 100% identical to pre-mortem, differing in 0 lines, and is treated as a copy.